The majority of American teens believe in God and worship in conventional congregations, but their religious knowledge is remarkably shallow and they have a tough time expressing the difference that faith makes in their lives, a new survey says.

However the National of Study of Youth and Religion did conclude that "religion really does matter" to teens.

The research found that devout teens hold more traditional sexual and other values than their nonreligious counterparts and are better off in emotional health, academic success, community involvement, concern for others, trust of adults and avoidance of risky behaviour.

The four-year effort was conducted by 133 researchers and consultants led by sociologist Christian Smith of the University of North Carolina at Chapel Hill. Smith reports the full results in the new book "Soul Searching: The Religious and Spiritual Lives of American Teenagers" (Oxford University Press).

On most of the measured criteria, Mormon youths — whose church runs daily high school religion classes — were the most engaged in practicing their faith, followed in order by evangelical Protestants, black Protestants, mainline Protestants, Catholics and Jews.

An entire chapter of the book examines Catholic youths, described as fairly weak "on most measures of religious faith, belief, experience and practice." The problem is attributed largely to ineffective youth programs and "the relative religious laxity of their parents."

Meanwhile Tasmanian Senator Brian Harradine has focused on teen abstinence in a Herald-Sun opinion piece that was published yesterday by On Line Opinion.

Senator Harradine accused health authorities of double standards in their pushing teens towards total abstinence from smoking, while advocating safe sex strategies such as condoms.

"Unlike the approach to smoking, the view shared by the well-funded sex-ed establishment is that if teenagers are experimenting with sex, then we'll affirm their choice and help make it 'safe' and 'positive'," he said in his effort to promote abstinence. "Those who want to impose a uniform sex-education curriculum on Australian school children ignore that there is another powerful, well-documented, well-researched viewpoint."

Senator Harradine said hundreds of new websites - secular ones like abstinence.net, and faith-based ones like pureloveclub.com - provide teens and their educators with up-to-date information, reinforcing the positive health and emotional benefits of not engaging in early sex.